Network Slice Availability Signaling in RAN Notification Area
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Solution Overview
Problem
In the 5G mobile communication system, a UE in the RRC_INACTIVE state faces challenges in determining the availability of desired network slices in target cells during cell reselection, which can lead to inefficient mobility management and potential service disruptions.
Innovation Solution
The system includes a base station and a radio terminal that exchange information about network slice availability within the RAN notification area, allowing the UE to check if configured network slices are available in reselected cells, enabling informed state transitions and optimal resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE performs cell reselection in RRC_INACTIVE state without checking network slice availability, then mobility operation is simplified, but service continuity is compromised when desired network slices are unavailable in target cells
Solution Approach 1:
The base station performs preliminary action by determining network slice availability in target cells before the UE executes cell reselection. The base station includes slice availability information in the RAN notification area configuration, enabling the UE to make informed reselection decisions without actually performing the complex slice availability check itself, thus resolving the contradiction between operational simplicity and service continuity.
Solution Approach 2:
The base station acts as an intermediary that provides slice availability information to the UE. Instead of requiring the UE to directly check slice availability (which would complicate its operation), the base station mediates this information through the RAN notification area configuration, allowing the UE to maintain simple cell reselection operation while ensuring service continuity through informed decisions.
2Reliability
If the UE frequently transitions to RRC_CONNECTED state to check network slice availability, then service continuity is maintained, but energy consumption increases
Solution Approach 1:
The base station performs the energy-intensive slice availability determination action in advance, before the UE needs to make reselection decisions. By including this pre-determined information in the RAN notification area configuration, the UE can remain in the low-power RRC_INACTIVE state while still accessing slice availability information, thus maintaining service continuity without the energy cost of frequent state transitions.
Solution Approach 2:
The base station provides slice availability information as part of its normal operation in the RAN notification area configuration, essentially serving the UE's information needs without requiring the UE to actively request or transition to RRC_CONNECTED state. This self-service approach maintains service continuity while minimizing energy consumption.
3Adaptability or versatility
If the base station determines network slice availability for each cell in the RAN notification area, then the UE can make informed reselection decisions, but system complexity increases
Solution Approach 1:
The base station performs slice availability determination as a preliminary action when configuring the RAN notification area, rather than performing it dynamically during each reselection decision. This pre-computation approach, while adding some initial complexity, eliminates the need for complex real-time slice availability checks during reselection, actually reducing overall system complexity while maintaining accurate reselection decisions.
Solution Approach 2:
The base station determines slice availability for all cells in the RAN notification area (excessive action) and includes this information in the RAN notification area configuration. This comprehensive approach provides the UE with all necessary information for informed reselection decisions, and while it increases initial processing, it simplifies the reselection process itself by providing complete information upfront.
Data Source
AI summary
A base station (1) controls state transitions of a radio terminal (2) among first to third RRC states. In addition, the base station (1) explicitly or implicitly informs the radio terminal (2) about whether a network slice configured in the radio terminal (2) for data communication at least in the first RRC state is available in each cell included in a RAN notification area configured by a RAN (3). It is thus, for example, possible to allow a radio terminal in a first state (e.g., RRC_INACTIVE state) to be easily aware of the availability of network slices in a cell to be reselected or a reselected cell.